RBI says it has received complaints about notes of 1,000 rupee denomination without the security thread being in circulation and has asked banks not to issue them in case these are found.Reserve Bank said it has informed all banks in Mumbai region not to issue such notes if found in stock and to provide exchange value to the customer who approaches with such a note, if it is otherwise genuine. RBI said, the total number of such notes with public may not be more than 500 pieces.